IS 1876:2005 IEC 60052 (2002) ( Reaffirmed 2004 ) WTmE'WJ "+m-m-diinkhm 3im!-mi Indian Standard VOLTAGE MEASUREMENT BY MEANS OF STANDARD AIR GAPS ( First Revision) ICS 19.080 0 61S 2005 BUREAU MANAK OF BHAVAN, INDIAN STANDARDS SHAH 110002 ZAFAR MARG 9 BAHADUR NEW DELHI October 2005 Price Group 9 High Voltage Engineering Sectional Committee, ET 19 > NATIONAL FOREWORD This Indian Standard (First Revision) which is identical with IEC 60052:2002 `Voltage measurement by means of standard air gaps' issued by the International Electrotechnical Commission (lEC) was adopted by the Bureau of Indian Standards on the recommendations of High Voltage Engineering Sectional Committee (ET 19) and approval of the Electrotechnical Division Council. The text of the IEC Standard has been approved as suitable for publication as an Indian Standard without deviations. Certain terminology and conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following: a) Wherever the words `International be read as `Indian Standard'. Standard' appear referring to this standard, they should b) Comma (,) has. been used as a decimal marker while in Indian Standards, practice is to use a point (.) as the decimal marker. Standard has been retained while adopting the current Only the English text of the International Standard. it as an Indian In this adopted standard, reference appears to certain International Standards for which Indian Standards also exist. The corresponding Indian "Standards, which are to be substituted in their respective places, are listed below along with their degree of equivalence for the editions indicated: International Standard Corresponding Indian Standard Degree of Equivalence Identical IEC 60060-1 (1 989) High-voltage test techniques -- Part 1 : General definitions and test requirements IEC 60060-2 (1 994) High-voltage test techniques -- Part 2 : Measuring systems 1S 2071 (Part 1) :1993 High-voltage test techniques : Part 1 General definitions and test requirements (second revision) IS 2071 (Part 2) :1974 Methods of high voltage `testing : Part 2 Test procedure (first revision) Technically equivalent For the purpose of deciding whether a particular requirement of this standard is complied with the final value observed or calculated, expressing the result of a test or analysis shall be rounded off in accordance with IS 2 : 1960 `Rules for rounding >ff numerical values (revised'. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. Is 1876:2005 IEC 60052 (2002) Indian Standard VOLTAGE MEASUREMENT BY MEANS OF STANDARD AIR GAPS ( First Revision) 4 Scope air tEC 60052 sets forth recommendations concerning the construction and use of standard gaps for the measurement of peak values of the following four types of voltage: a) b) c) d) alternating full lightning switching voltages impulse of power frequencies; voltages; impulse voltages; direct voltages. in accordance with this standard with IEC 60060-2 and are primarily systems. represent IEC standard intended for performance Air gaps constructed and used measuring devices in accordance checks of high voltage measuring 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60060-1:1989, /+igh-vo/tage test techniques - Part 1: General definitions and test requirements IEC 60060-2:1994, High-vo/tage test techniques - Part 2: Measuring systems 3 Definitions vacant 4 Standard sphere-gap The standard sphere-gap is a peak voltage measuring device constructed and arranged in accordance with this standard. The points on the two spheres which are closest to each other are called the sparking points. Figures 1 and 2 show two arrangements, one of whioh is typical of sphere-gaps with a vertical axis and the other of sphere-gaps with a horizontal axis. 4.1 Requirements on shape and surface conditions the same diameter D, their shanks, leads for connection to the point at are 2-5-6,25-10-12,5-15the spheres is designated S. The standard sphere-gap consists of two metal spheres of operating gear, insulating supports, suppoding frame and which the voltage is to be measured. Standard values of D 25 ­ 50-75-100-150 and 200 cm. The spacing between 1 IS 1876:2005 IEC 60052 (2002) The spheres shall be carefully uniform as possible. made so that their surfaces are smooth and their curvature is as The tolerances on size and shape need usually only be checked when supplied and any suitabie instrument (e.g. spherometer) may be used. the spheres are first The diameter of each sphere shall not differ by more than 2 % from the nominai vaiue. The spheres shail be reasonably free from surface irregularities in the region of the sparking point. A medium grade mechanical surface finishing (roughness R~,X beiow 10 pm) is considered to be adequate. The region of the sparking point is defined by a circie such as wouid be drawn on the spheres by a pair of dividers set to an opening of 0,3 D and centred in the sparking point. When visual NOTE the sphere-gap inspection. Any minor damage is used, it wili normally be sufficient to examine the surface by touch and on the non-adjacent hemispherical surfaces does not alter the sphere-gap performance. 4.2 4.2.1 General Vertical arrangement gap of a sphere-gap for measurement When the spheres are arranged verticaiiy, the shank of the high-voitage sphere shail be free from sharp edges or corners and the diameter of the shank shali not exceed 0,2 D over a iength D. This requirement is made in order to reduce the infiuence of the high-voitage shank on the disruptive discharge voitage. If a stress distributor (corona shieid) is used at the end of the shank, its greatest dimension, perpendicular to the axis of the spheres, shaii not exceed sphere. 0,5 D and shail be at ieast 2 D from the sparking point of the high-voltage The earthed shank and the operating therefore iess important. Figure gear have a smaiier effect and their dimensions are 1 gives the iimits of size of the components-of shanks shouid gap be visually in line. a typicai verticai sphere-gap. The sphere 4.2.2 Horizontal When the spheres are arranged horizontaiiy, the iimiting dimensions are given in figure 2. They are the same for both sides of the gap. The sphere 4.2.3 shanks shouid be visualiy above in iine. the horizontal earth plane above of a typical sphere-gap Height of the spheres The height A of the sparking point of the high-voltage sphere laboratory fioor shall be within the iimits given in tabie 1. the earth piane of the if the sphere-gap is mounted with the earthed sphere nearest to the ceiiing, and if other surfaces such as waiis and the fioor are at a considerably greater distance, then the ceiling shaii be regarded as the horizontal piane, from which the distance A is measured downwards. 2 IS 1876:2005 lEC 60052 (2002) 4.2.4 Clearance around the~pheres The distance from the sparking point of the high-voltage sphere to any extraneous objects (such as ceiling, walls, and any energized Qr earthed equipment), andalso to"the supporting frame work for the spheres, if this is made of conducting material, shall not be less than the below, B should not be less than 2 D, value of distance B in table 1. Except as permitted regardless of the value of S. Supporting frameworks for the spheres made of insulating material are exempt from this requirement, provided that they are clean and dry and that the spheres are used for the measurement of alternating or impulse voltages only. The distance B between the sparking in point of the high-voltage sphere and the frarnework- may then be less than is prescribed table 1, however, it shall nol be less than 1,6 D. The peak values of disruptive discharge voltages in tables around the spheres within the limits given in table 1. Table Sphere dksmeter cm D Minimum value height A 7D 6D 5D 4D 4D 3,5 D 3D 3D 2 and 3 are valid for clearances 1of Clearance limits of Minimum value distance B 14s 12 s 10s 8s 8S 7s 6S 6S of Maximum value height ,4 9D 8D 7D 6D 6D 5D 4D 4D UP to 6,25 10-15 25 50 75 100 150 200 The test minimum deviation disruptive calibrated The circuit - conditions may make it impossible for the values of A and B to comply with the requirements. Such sphere-gaps can be used, providing that, either the conventional z meets the requirements of clause 5, or, that the uncertainty in the values for discharge in tables 2 and 3 are suitably increased. Such sphere-gaps could be under laboratory conditions as indicated in annex D. should be arranged discharge so that at the test voltage there is no disruptive no visible by B, no visible to other objects, from the high-voltage objects lead or the shank extending within the space defined leader discharge 4.3 discharge from other earthed into the space defined by B. Connections shall be connected in accordance with the requirements specified in The sphere-gap IEC 60060-2. 4.3.1 Earthing (1'te sphere normally shall be connected directly to earth. between the sphere and earth for special purposes. Low ohmic shunts may be connected 3 IS 1876:2005 IEC 60052 (2002) 4.3.2 High-voltage conductor The high-voltage conductor, including any series resistor not in the shank itself, shall be connected to a point on the shank at least 2 D away from the sparking point of the high-voltage sphere. Within the region where the distance to the sparking point of the high-voltage sphere is less conductor (including the series resistor, if any) must not pass through than B, the high-voltage the plane normal to the axis of the sphere-gap and situated at a distance 2 D from the sparking point of the high-voltage sphere. See figures 1 and 2 where the plane is shown. 4.3.3 Protective resistor for measurement of alternating and direct voltages Precautions should be taken to minimize pitting of the spheres and to prevent superimposed oscillations, which may cause erratic disruptive discharges. For this purpose, a resistance of 0,1 MQ to 1 MC? shall be connected in series with the sphere-gap. This range of resistance values applies to measurements of direct voltages and of alternating voltages at power frequencies, because the values of the resistance results in a negligible voltage drop. The protective resistor should connected directly to it. be placed as near as possible to the shank of the sphere and When streamer discharges are present in the test circuit, series resistance is particularly important in order to reduce the effect of the consequent transient over-voltage on the operation of the sphere-gap. When these discharges are not present either in the test circuit or in the test specimen, the value of resistance may be reduced to a value which prevents excessive burning of the spheres by disruptive discharges. 4.3.4 Protective series resistor for measurement of impulse voltages Series resistance is needed with large diameter spheres to eliminate oscillations in the spheregap circuit which may cause a higher voltage to occur between the spheres and, if connected, across the test object. This phenomenon is usually of minor importance for smaller spheres, unless they are used with long connecting leads. Series resistance may also be needed to reduce the steepness of the voltage collapse which might introduce undesirable stresses in the test object. The resistor shall have a non-inductive construction (not more than 30 pH) and its resistance should not exceed 500 s2. For the position of the resistor in the circuit, see 4.3.2. 5 Use of the sphere-gap A sphere-gap is an IEC standard measuring device when the conventional deviation z (4.4.5 of IEC 60060-1) at the time of use is less than 1 % for alternating voltages at power frequency impulse voltages. The and lightning impulse voltages and less than 1,5 `?Aofor switching of conventional deviation z is affected by the condition of the sphere surfaces, the availabi;lty free electrons (sufficient irradiation), the dust contained in the air and the measurement procedures. 4 IS 1876:2005 IEC 60052 (2002) 5.1 Condition of the sphere surfaces The surfaces of the spheres in the neighborhood of the sparking points shall be cleaned and dried but need not be polished. In normal use the surfaces of the spheres become rcwghened and pitted. The surface should be rubbed with fine abrasive paper and the resulting dust removed with lint-free cloth; any trace of oil or grease should be removed with a -solvent. If the spheres become excessively roughened or pitted in use, they shall be repaired or replaced. Moisture humidity may condense on the surface of the sparking causing measurements to become erratic. points in conditions of high relative Minor damage to the surface of the sphere beyond the region likely to affect the use of the sphere as a measuring device. NOTE The requirement been met. for the conventional deviation : ensures of sparking point (see 4.1) is not that the requirements for surface conditions have 5.2 Irradiation The disruptive discharge voltage of a sphere-gap depends upon the -av.amiability of free electrons in the gap between the spheres at the moment of application of voltage. Actions should be taken if the requirements for conventional deviation are not met. Direct exposure of a sphere-gap to the light from the impulse generator polarity corona of the used or separate source, may be sufficient. gaps, or to negative Irradiation is usually required for measurements below 50 kV peak for all sphere diameters, and for measurement of voltages with spheres of 12,5 cm diameter and less for all voltage shapes. Methods of arranging irradiation are described in annex C. NOTE When sufficient irradiation is not available, discharge in the.tables 2 and 3 should be increased. the uncertainty associated with the values for disruptive 5.3 Voltage measurements A measurement of voltage by means of sphere-gap consists of establishing the relation between a voltage in the test circuit, as measured by the standard air gap, and the indication of a voltmeter in the control circuit, or the peak value of the voltage obtained from a suitable measuring or recording device connected to the low voltage side of a measuring system. The spacing between the spheres shall be measured by a method consistent with the overall uncertainty of the voltage measurement. Unless the contrary can be shown, this relation ceases to be valid if the circuit is altered in any respect other than due to a charrge of the spacing of.the spheres. 5.3.1 Measurement of peak value of alternating voltage at power frequency The voltage shall be applied with an amplitude low enough not to cause disruptive discharge when the supply is energized, and it is then raised sufficiently slowly for the low-voltage indicator to be read accurately at the instant of disruptive discharge of the gap. A minimum number of 10 successive disruptive discharge voltages shall be recorded in order z can be evaluated. The value of the that the mean value and conventional deviation conventional deviation z shall be less than 1 `A of the mean value. The interval between voltage applications should be not less than 30 s. 5 IS 1876:2005 IEC 60052 5.3.2 (2002) of peak value of full Iightnrng and switching impulse voltages z Measurement U50 and the conventional deviation The 5094. disruptive discharge voltage z shall be not more than determined. The value of the conventional deviation lightning impulse voltages and not more than 1,5 % for switching impulse voltages. This c-an be done by a multiple level test. A minimum of 10 voltage voltage levels in approximately 1 Y. steps of the expected disruptive deviation Z. to obtain U50 and to check the conventional It can also be done by an up-and-down-test at approximately 1 ?4. steps of the expected with a minimum voltage. number 1 Y. shall be for full applications at each of five discharge value is needed of 20 voltage applications U50 The criterion for the conventional deviation z shall be checked by applying 15 impulses at a and U50-1,5 Y. for switching impulse voltage level of U50-I ?40 for lightning impulse voltages voltages. There shall be not more than two disruptive discharges. The interval between voltage applications shall be not less than 30 s. range, the criterion for the conventional NOTE If, in a particular test, the sphere-gap deviation : should be checked for the smallest is used over a gap spacing and largest gap distances. 5.3.3 Measurement of direct voltages measurement of direct voltages because of the particles in the air which cause erratic disruptive is recommended for the measurement of direct gin-s. Sphere-gaps are not recommended for the erratic behavicmr of these gaps due to fibrous discharges at low voltages. The rod-rod gap voltage in a humidity range from 1 gm-3to 13 When a rod-rod-gap cannot be used, the following procedure for sphere-gaps is recommended. A constant air flow of at least 3m/s should be maintained across the gap. The voltage shall then be applied with an amplitude low enough not to cause disruptive discharge when the supply is energized, and it is then raised sufficiently slowly for the low-voltage indicator to be read accurately at the instant of disruptive discharge of the gap. The highest stable voltage level at which the breakdown occurs is the value given in table 2. for NOTE The spurious nature of direct voltage breakdown of a sphere-gap might require the tests to be continued a very large number of voltage applications until a stable upper limit has been established. 6 Reference values in tables 2 and 3 spacings between spheres are given for temperature and pressure: in tables 2 The disruptive discharge voltages and 3 for the standard atmospheric temperature pressure t(J = 20 `c; for various conditions b.= 101,3 kPa. obtained under of 8,5 gin-3. conditions of absolute humidity between The values in tables 2 and 3 were 5 gin-3 and 12 gin-3 with an average 6 IS 1876:2005 IEC 60052 (2002) Table 2 gives in kV for: alternating ­ full lightning and the peak value of disruptive discharge voltages (usO values in impulse tests.) voltages at power frequencies; impulse voltages of negative polarity (as defined in IEC 60060-1); and switching direct voltages of both polarities. discharge voltages (U50 values) in kV for: in IEC 60060-1. Table 3 gives the peak value of disruptive full lightning and switehin_g impulse voltages of positive of impulse polarity as defined Tables 2 and 3 are not valid for the measurement voltages below 10 kV. 3 have been derived from NOTE Annexes A and B give the range of voltages over which tables 2 and experiments, and can be presumed to be within the uncertainty limits given in 6.1. 6.1 Accuracy of values in tables 2 and 3 been accepted -as an international consensus reference The values in tables 2 and 3 have standard of measurement. 6.1.1 Alternating and impulse voltages 2 and 3 have an estimated The values for uncertainty of 3 !Ao for disruptive discharge voltage given in tables a level of confidence not less than 95 ?40. between Some values are given in tables 2 and 3 for spacings confidence is assigned to those values in brackets, As it may be difficult to measure spacing to diameter is very small, 0,05 D. 6.1.2 Direct voltage information to estimate 0,5 D and 0,75 D. No level of and adjust the gap with sufficient it is recommended that the spacing accuracy if the ratio of should not be less than There is insufficient voltages. 6.2 Air density the uncertainty in measurement values for direct correction factor conditions 2 and 3 by Disruptive discharge voltages corresponding to a given spacing under atmospheric other than those specified above are obtained by multiplying the values in tables a correction factor corresponding to the relative air density 3. The relative air density dis defined by ~ 8=--X 273+t0 (1) b. where the atmospheric pressures 273+t b and b. are expressed in degrees Celsius. in the same units (kPa); t and to are the temperatures 7 IS 1876:2005 IEC 60052 (2002) 6.3 Humidity correction factor of a sphere-gap increases with absolute humidity at a rate of The disruptive discharge 0,2 % per gin-3. voltage The average value of absolute humidity h under which the values in tables 2 and 3 were obtained is 8,5 gin-3. The values in tables 2 and 3 shall be corrected "for humidity by multiplying the values in those tables by the humidity correction factor k given by the following equation: k = l+(0,002x(h/ with the ambient absolute humidity h in gin-3. d - 8,5)) (2) 7 7.1 Standard General rod-rod gap for measurement of a rod-rod gap of direct voltage arrangement The general arrangement of a rod-rod or figure 3b (horizontal gap). gap shall be as shown in either figure 3a (vertical gap) The rods shall be made of steel or brass, with a solid square section, sides between 10 mm and 25 mm and have a common axis. The ends shall be cut at right angles to the axis leaving the edges sharp in order to get a reproducible breakdown mechanism. The clearance from the tip of the high voltage ground plane, shall be not less than 5 m. 7.2 Reference values and negative and horizontal direct voltage gap by: at standard to earthed objects and walls, other than the UO for positive The disruptive discharge voltage reference atmosphere is given, for either the vertical Uo =2+0,534xd where U. is in kilovolts and d is the gap spacing (3) in millimetres. Equation (3) is valid for gap distances d between 250 mm and 2500 mm and for a humidity range h/5 between 1 gin-z and 13 gin-3. Under these conditions, the disruptive discharge of 3 ?40 for a level of confidence not less than 95 `A. voltage U. has an estimated uncertainty The rod-rod gap shall not be used as an approved measuring device at gap spacing less than 250 mm because of the absence of streamer pre-discharges. There is no experimental evidence to support its use at gap spacings greater than 2500 mm. 7.3 Measurement procedure and raised 1 min. so that the The spacing time interval d between the rods shall be set and the voltage applied between 75 % and 100% of the discharge voltage is about 8 IS 1876:2005 [EC 60052 (2002) Ten readings of the voltage at the instant of sparkover shall be taken with the voltage system. The voltage, at standard reference atmosphere, indicating device of the measuring corresponding to the mean of these 10 values is given by equation (3). This voltage shall be corrected for the actual atmospheric conditions by taking into account the air density d (see 6.2) and the humidity correction factor k given by the following equation: k=l+(o,014 x(/1/d-11)) [4) for a humidity range h/i3 between 1 gin-3 and 13 gin-3. under actual conditions with h are reported to standard the temperature t, the reference atmosphere Breakdown voltage values U measured b and the -absolute humidity pressure as-follows: UO=U/(3xk) (5) 8 Use of standard air gaps for performance checks of approved measuring systems When a standard air gap is used to make performance checks on a measuring system whose performance is known only insofar as it meets the requirements of an approved measuring system, the two elements of the check circuit will each have an assigned uncertainty of 3 ?Ao and therefore differences exceeding this figure could arise in the comparison. However, when performance checks on the same apprOved measuring the differences between subsequent measurements, after correction conditions, can be expected to be appreciably less than 3 `A. system are repeated, for all atmospheric 9 IS 1876:2005 IEC 60052 (2002) Table 2- Peak values in kV for alternating impulse voltages Spheregap spacing cm of disruptive discharge voltages (U50 values in impulse tests) voltages at power frequencies, full lightning and switching of negative polarity and direct voltages of both polarities Sphere diameter cm 25 60 75 100 160 200 2 5 6,26 12,6 15 0,05 0,10 0,15 0,20 0,25 `,8 ,7 i,4 ,0 1,6 1,0 1,6 0,30 0,40 0,50 0,60 0,70 1,2 4,4 7,4 !0,4 !3,2 11,2 14,3 17,4 ~o,4 23,4 14,2 17,2 20,2 23,2 16,8 19,9 23,0 16,8 19,9 ?3,0 16,8 19,9 23,0 0,80 0,90 1,0 1,2 1,4 !5,8 !8,3 10,7 35,1) 38,5) ?6,3 z9,2 32,0 37,6 !2,9 26,2 ~g,l 31,9 37,5 $2,9 26,0 28,9 31,7 37,4 42,9 ~6 ,o ~8,9 31,7 37,4 $2,9 26,0 28,9 31,7 37,4 42,9 31,7 37,4 $2,9 1,5 1,6 1,8 2,0 2,2 40,0) $5,5 48,1 53,0 57,5 51;5 t5,5 $8,1 53,5 58,5 53,0 45,5 48,1 53,5 59,0 64,5 45,5 48,1 53,5 59,0 54,5 45,5 48,1 53,5 59,0 64,5 $5,5 48,1 53,5 59,0 34,5 i9,0 i4,5 59,0 54,5 2,4 2,6 2,8 3,0 3,5 55,5 :69,0) :72,5) :75,5) [82,5) 57,5 72,0 76,0 79,5 [87,5) 69,5 74,5 79,5 84,0 95,0 70,0 75;0 30,0 35,0 37,0 70,0 75,5 80,5 85,5 98,0 70,0 75,5 !31,0 96,0 99,0 ?(), () 70.0 75,5 51,0 36,0 39,0 16,0 )9,0 ?5,5 11,0 56,0 19,0 4,0 4,5 5,0 5,5 6,0 [88,5) [95,0) [101) [107) 105 115 123 (131) (138) 108 119 129 138 146 110 122 133 143 152 112 125 137 149 161 112 125 138 151 164 112 125 138 151 164 112 125 138 151 164 138 151 164 10 IS 1876:2005 IEC 60052 (2002) Table Spheregap spacing cm i,5 2 (continued) Sphere diameter cm 25 73 B4 95 06 26 50 77 89 02 14 39 75 I 77 I 90 ?03 ~15 ?40 100 77 90 !03 !15 !41 150 I 77 I 90 ?03 ~q5 ?41 200 2 5 6,25 10 144) 150) 155) 12,5 I 54) 161) 168) I 74) 185) 16 61 69 77 185) `,0 `,5 1,0 1,0 19.8) 0 1 2 13 14 195) 209) 2+9) 229) 44 61 75 289) 302) 63 86 09 31 53 265 290 315 339 363 !66 ?92 }18 ~42 566 ?66 ?92 }18 542 )66 266 292 318 342 366 15 16 17 18 19 314) 326) 337) 347) 357) i73 387 410 432 453 473 390 !14 $38 $62 $86 390 $14 !38 $62 486 390 414 438 462 486 i92 ,11 129 145 ?0 ?2 M 26 28 366) 160 189 i15 540) 565) 492 530 565 600 635 510 555 595 335 575 510 560 310 355 700 510 560 610 660 705 30 32 34 36 38 585) 605) 625) 640) 655) 665 695 725 750 (775) 710 745 780 B15 B45 745 790 B35 B75 915 750 795 840 685 930 40 45 50 55 60 670) (800) (850) (895) (935) (970) 875 945 1010 (1060) (1110) 955 1050 1130 1210 1280 975 1080 1180 1260 1340 65 70 75 (1160) (1200) (1 230) 1340 1390 1440 1410 1480 1540 11 IS 1876:2005 IEC 60052 (2002) Table Spheregap spacing cm 10 15 2 (continued) Sphere diameter cm 25 "60 75 100 150 (1 490) (1540) 200 1600 1660 2 5 6,2s 10 12,5 15 )0 I 00 110 I 20 I 30 (1580) (1660) (1730) (1800) 1720 1840 (1940) (2020) (2100) 140 I 50 , (2180) (2250) UOTE 1 NOTE 2 Values Figures are not valid for impulse voltages in brackets, below 10 kV. which are for spacings of more than 0,5 D, are of larger uncertainty. 12 IS 1876:2005 IEC 60052 (2002) Table 3- Peak values of disruptive discharge voltages (U50 values in impuise tests) in kV for fuii iightning and switching impuise voitages of positive poiarity Spheregap spacing cm Sphere diameter cm 2s 50 75 100 160 200 2 5 6,25 10 12,5 16 ),05 },10 },15 ),20 ),25 ),30 ),40 ),50 ),60 ),70 1,2 4,4 7,4 0,4 3,2 1,2 4,3 7,4 !0,4 !3,4 4,2 7,2 !0,2 !3,2 16,8 19,9 23,0 16,8 19,9 ~3,0 16,8 19,9 ~3,0 ),80 ),90 I ,0 I ,2 I ,4 ;5,8 8,3 10,7 35,1) 38,5) !6,3 Kl,2 )2,0 )7,8 13,3 !6,2 !9,1 )1,9 17,6 13,2 26,0 28,9 31,7 37,4 42,9 26,0 28,9 31,7 37,4 42,9 ~6,0 28,9 31,7 37,4 $2,9 31,7 37,4 42,9 I ,5 1,6 1,8 ?,0 Z,2 40,0) 16,2 19,0 54,5 59,5 $4,0 15,9 18,6 54,0 59,0 >4,0 45,5 48,1 53,5 59,0 64,5 45,5 48,1 53,5 59,0 64,5 45,5 $8,1 53,5 59,0 64,5 45,5 48,1 53,5 59,0 64,5 59,0 94,5 59,0 64,5 2,4 2,6 2,8 3,0 3,5 $9,0 :73,0) :77,Q) :81 ,0) :90,0) >9,0 73,5 78,0 32,0 :91 ,5) 70,0 75,5 80,5 85,5 97,5 70,0 75,5 80,5 85,5 98,0 70,0 75,5 60,5 65,5 98,5 70,0 75,5 81,0 86,0 99,0 70,0 75,5 61,0 B6,0 99,0 70,0 75,5 81,0 86,0 99,0 B6,0 99,0 4,0 4,5 5,0 5,5 6,0 [97,5) [101) [108) [1 15) 109 120 130 (139) (148) 110 122 134 145 155 111 124 136 147 158 112 125 138 151 163 112 125 138 151 164 112 125 t38 151 164 112 125 138 151 164 138 151 164 6,5 (156) (164) 168 175 177 177 177 177 13 IS 1876:2005 IEC 60052 (2002) Table 3 (continued) Spheregap spacing cm Sphere diameter cm 26 187 I 99 ~j 1 ~33 60 189 202 214 239 76 190 203 215 240 2 6 6,2S 10 163) 170) 12,6 173) 181) 189) 203) 16 78 87 196) 212) 100 I 90 203 215 241 150 190 203 ~q5 241 200 7,0 7,5 1,0 ),0 10 11 12 13 14 215) 226) 238) 249) ~54 ~73 291 :308) :323) 263 287 311 334 357 265 290 315 339 363 266 292 318 342 366 266 292 318 342 366 266 292 318 342 366 15 16 17 18 19 :337) :350) :362) :374) :385) 380 402 422 442 461 387 411 435 458 482 390 414 438 462 486 390 414 $38 $62 486 390 414 438 462 486 20 22 24 26 28 :395) 480 510 540 570 (595) 505 545 585 620 660 510 555 600 645 685 510 560 510 555 700 510 560 610 660 705 30 32 34 36 38 (620) (640) (660) (680) (700) 695 725 755 785 (810) 725 760 795 830 865 745 ?90 B35 B80 925 750 795 840 885 935 40 45 50 55 60 (715) (835) (890) (940) (985) (1020) 900 980 965 1060 1150 980 1090 1190 1290 1380 (1100) (1150) 1240 1310 65 70 75 (1200) (1240) (1280) 1380 1430 1480 1470 1550 1620 14 IS 1876:2005 IEC 60052 (2002) Table Spheregap spacing cm 80 85 3 (continued) Sphere diameter cm 76 2 5 6,26 10 100 150 (1530) (15ao) 200 1690 1760 90 (1630) 1820 100 110 120 130 (1720) (1790) (1860) 1.930 (2030) (2120) (2200) 140 150 (2280) (2350) NOTE The figures in brackets, which are for spacings of more than 0,5 D, are of larger uncertainty. 15 IS 1876:2005 IEC 60052 (2002) \ X ( -­-> 4 /- i II s0,5D ~ I I / I x \ x`1 1 000 -7 ~250sds2WXt il II ii ;i [i I -1 Insulator I [ ii il 1! Figure 3b - Horizontal Figure 3- arrangement of rod-rod gap gap Arrangement for rod-rod 18 IS 1876:2005 IEC 60052 (2002) Annex A (informative) Range of experimental calibrations for sphere-gaps Tables 2 and 3 are partly derived from experiments reported There is no experimental proof of their accuracy at voltages table A. 1. Table A.1 - Experimental calibrations Highest voltage kV rIeak Wemating Wernating lirect lirect voltage of power frequency voltage of power frequency 1700 1400 800 1300 2580 in the references given below. higher than the values given in of the sphere-gap Kind of voltage Reference Transactions AlEE Vol. 71 (1952), P.655 p.209 P.209 Part Ill, p.455 JIEE vol. 82, (1938), voltage + (sphere-gaps) Zeit. techn. Phys. 18 (1937), Zeit. techn.Phys."18 Transactions Part Ill, p.455 (t937), voltage - (sphere-gaps) + (lightning) repulse voltage AIEE Vol. 71(1952) repulse voltage - (lightning) 2410 Transactions Part Ill, P.455 AIEE Vol. 71(1952) repulse voltage + (switching) Wernating Jndamped voltage of high frequency alternating voltage 1200 ELECTRA No 136, June 1991, P.91-95 p.92 (see Note 1) P.1314 p.491 p.525 p.322 P.123 ETZ Vol. 60 (1939), (See Note 2) JAIEE Vol. 46 (1927), >f high frequency I I I voltage Idem Arch. Elektr. Vol. 14 (1925), Arch. Elektr. Vol. .24 (1930), Arch. Elektr. Vol. 25 (1931), Arch. Elektr. Vol. 26 (1932), Ann. Phys. 19 (1906), P.1016 Damped alternating of high frequency I Arch. Elektr. Vol. 16 (1926), Arch. .Elektr. Vol. 20 (1928), p.496 p.99 NOTE 1 This reference contains a summary of the voltages made over a range of voltages and frequencies of most of these individual calibrations. calibrations with damped and undamped high-frequency up to 1939. The other references in the list give the details N"OTE 2 From the information in the references, which is incomplete and sometimes table.2 can be used without serious error for the measurement of undamped alternating to 20 kl-iz but only up to about 15 kV peak. At higher frequencies this voltage is reduced. conflicting, it appears that voltages at frequencies up The references atso show that table 3 can be used for the measurement of damped alternating voltages frequencies up to 500 kHz, but again with the restriction that the voltage should not exceed 15 kV peak. at 19 1S 1876:2005 IEC 60052 (2002) Annex B (informative) Procedure by which the values in tables 2 and 3 have been derived from national standards and other sources NOTE The content of this annex is a reproduction of the original "Appendix B from the former IEC 52:1960. At the meeting of Technical Committee No. 42 in Munich in 1956, should be prepared which could be accepted internationally. Apart from certain exceptions, which new tables were to be the mean of: a) b) the values the values which were accepted in A.S.A. standard are noted below, it was agreed that new tables the disruptive discharge voltages in the by the IEC in Paris in July 1939; (after adjustment for temperature). the disruptive discharge was increased. without introducing other C 68.1 (1953) The calculation of the mean resulted in a few anomalies; in particular voltages of small gaps varied rather irregularly as the sphere diameter These anomalies anomalies. The exceptions have been removed as far as was possible mentioned above are listed below: for spheres of 2, 5, 10 and 15 cm. 1) No data are given in the ASA standard The IEC figures of 1939 for spheres of 5, 10 and 15 cm have therefore been included in the present tables without any changes other than the minor adjustments referred to above. 2) The figures for 2 cm spheres in the IEC agreement of 1.939, which were not applicable to positive impulses, were later found to be inaccurate at spacings up to 1 cm. A new calibration has therefore been inserted, based on JIEE, vol. 95 (1948), Part 11, P.309, but the values are not applicable to the measurement of impulses of either polarity below 10 kV. See Proc. `IEE, Part 11,Vol. 101, (1954), p:438, for evidence on this latter point. The IEC data of 1939 for voltages above 1400 kV are regarded as being less reliable than the most recently measured values in Ihe USA and these latter have therefore been adopted (see ASA C 68.1, 1953 and Transactions AlEE, vol. 71 (1952), Part Ill, p.455). The figures in tables 2 and 3 have been rounded B.1 - Rounding Value kV 3) off as indicated in tables Rounded kv off in table B.1: 2 and 3 Table off of values upto 50 to the nearest to the nearest to the nearest I to the nearest \ to the nearest 0,1 0,5 1 5 10 I I Over 50 and up to 100 Over 100 and UD to 500 / Over 500 andupto1000 I Over 1000 20 IS 1876:2005 lEC 60052 (2002) Annex C (informative) Sources of irradiation For alternating the presence measurement, voltage, irradiation may be obtained by corona of corona is very often not desired for other and therefore extra irradiation is recommended. exposure of a sphere-gap within the test circuit. reasons, e.g. partial However, discharge For impulse voltage, direct gaps may be sufficient. The extra the lamp spectrum therefore influence to the light from the impulse generator irradiation of the gap can be obtained by a spectrum falls in the far ultraviolet (UVC). falls in the ultraviolet, UVA or UVB, usually not recommended. The rating of the lamp as the effect of the irradiation. of the gap can also polarity. be obtained quartz tube mercury-vapour lamp where Mercury-vapour lamps where the lamp have insufficient irradiation and they are well as the actual distance from the gap The extra irradiation source with negative by pre-discharges from a DC corona 21 IS 1876:2005 IEC 60052 (2002) Annex D (informative) Uncertainty and calibration of sphere-gaps The value of 3 % forthe uncertainty overall uncertainty in a measurement in tables 2 and 3 is the dominant term in the estimation of voltage by means of sphere-gaps. of This value for uncertainty takes account of many factors including rounding of the results for the tables by as much as 1 %. This introduces an error of up to 0,5 YO for voltages above 10 kV and a greater error for voltages less than "1O kV. The uncertainty can be reduced significantly through a procedure of internal calibration of the sphere-gap by a laboratory with a suitable reference measuring system at the time of calibration of the laboratory's approved measuring system. A calibration of the sphere-gap, over a range of spacings, in terms of the voltage measured with a newly calibrated measuring system can be regarded as an internal calibration of the sphere-gap by the laboratory. The overall uncertainty of calibration should be significantly less than that associated with tables 2 and 3. From the time of calibration, any future difference in the measured voltage values between the measuring system and the sphere-gap, providing the conditions remain unchanged, should be evaluated for consistency with the reduced uncertainty figures obtained from the calibration procedure in order to indicate possible error in the measuring system. 22 IS 1876:2005 IEC 60052 (2002) Bibliography [1] [2] KU FFEL, E. The effect of irradiation under direct and a/fernating vo/tages, on the breakdown voltage of sphere-gaps Proceedings IEE, Vol. 106, 1959, p. 133-139 in air ALLIBON E, T. E. DRING, D. /nf/uence of radiation on sparkover crossed-cylinder gaps stressed with impulse voltages, Proceedings P.815 -821 KACHLER, A.J. Contribution of sphere-gaps, ISH Zurich, to the prob/em of impulse 1975, p.217 -221 vo/tage of sphere-gaps and IE E, Vol. 120, 1973, by means [3] [4] measurement GOURGOULIS, D. E., STASSINOPPOULOS, breakdown of sphere-gaps and sphere-rods, 1998, Vol. 145, No. .3, p.147 -151 FESER, K. HUGHES, R.C. Measurement No. 117, March 1988, p.23 -34 /nf/uence of irradiation on impu/se Proceedings IEE Sci. Meas. Technol. of direct vo/tage by rod-rod-gap, Electra [51 Annex [6] [7] A references HAGENGUTH, J.H. ROHLFS, A.F. DEGNAN, W.J. Sixty-Cycle and Impulse Sparkover of Large Gap Spacings, Transactions AlEE Vol, 71 Part Ill, January 1952, p.455-460 EDWARDS, F. S., SMEE, J. F. The Calibration of the Sphere Spark-Gap Measurement up to one million volts (effective) at 50 cycles, Journal, Electrical Engineers, Vol. 82, 1938, p.655-669 BOUWERS, V. A., KU NTKE, A. Ein Generator fur drei AWionen Zeitschrift fur techni.sche Physik, Vol. 18, 1"937, p.209-219 HAGENGUTH, for Voltage Institution of [8] [9] Vo/t G/eichspannung, of Large Gap Spacings, J.H. ROHLFS, A.F. DEGNAN, W.J. Sixty-Cyc/e and /mpu/se Sparkover Transactions AlEE Vol. 71 Part Ill, January 1952, p.455-46"0 by Means of [10] [11] GOCKENBACH, E. Measurement of Standard Switching /mpu/se Vo/tages Sphere-gaps (One Sphere Earthed), Electra No. 136, June 1.991, p.91 -95 JACOTTET, V.P. Zur Frage der Messung von Hochfrequenzspannungen spannungen ktirzester Dauer mit der Kuge/funkenstrecke, Elektrotechnische Vol. 60, Jan. 1939, p.92-97 und Stol.?Zeitschrift, [12] REUKEMA, L. E. The Relation Between Frequency and Spark-Over, Voltage in a SphereGap Vo/tmeter, Journal of the American Institute of Electrical Engineers, Vol. 46, 1927, p.1314-1321 GOEBELER, E. ~ber die dielektrischen Eigenschatlen der Luft und einiger fester lsoliermaterialien bei hochgespannter Hochfrequenz, Arch. Elektr. Vol. 14, 1925, p.491 -510 KAMPSCH ULTE, J. Luftdurchsch/ag Ubersch/ag mit 100000 Hertz, Arch. Elektr. Vol. 24, 1930, p.525-551 LASS EN, H. EINLEITUNG, A. Frequenzabh~ngigkeit Elektr. Vol. 25, 1931, p.322-332 MISER~, F. Luftdurchschlag bei Niederfrequenz Elektroden, Arch. Elektr. Vol. 26, 1932, .p. 123-126 ALGERMISSEN, Schwinguf?gen, I?OGOWSKI, spannungen, V.J. Annalen W. Arch. Wechse/spannung von 50 und [13] [14] [15] [16] [17] [18] [19] der f-unkenspannung und Hochfrequenz in Luft, Arch. an verschiedenen bei Luft schnellen bei Stoss-Vol. 20, Verhalt~is von Schlagweite und Spannung der Physik, Vol. 19, 1906, p.1 016-1029 Durchschlag bie Gasen, der Arch. Townsends Theorie und der Elektr. Vol. 16, 1926, p.496-508 Stos.sspannung und Durchsch/ag ROGOWSKI, W. 1928, p.99-106 Elektr. 23 IS 1876:2005 IEC 60052 (2002) Annex [20] [21] [22] B references American standard for measurement of voltage in dielectric tests, ASA Std. C68. 1, 1953 COOPER, R., GARFITT, gaps, Journal, Institution HARDY, diameter D. E. M., MEEK, J.M. The calibration of 2-cm diameter sphereof Electrical Engineers, Vol. 95 Part 11,1948, p.309 -311 The effect of irradiation on the calibration IEE, Vol. 101 Part 11,1954, p.438 -440 of 2-cm- D. R., BROADBENT, T.E. sphere-gaps, Proceedings 24 Bureau of Indian Standards institution established under the Bureau of hxfian Standards of standardization, in the country. marking Act, 1986 to promote certification of BIS is a statutory harmonious development of the activities matters and quality goods and attending Copyright BIS has the copyright to connected of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publication), 61S. Review of Indian Standards as the need arises on the basis of comments. that changes are needed, Standards are also Amendments no changes are issued to standards are needed; reviewed periodically; a standard along with amendments if the review indicates should ascertain is reaffirmed when such review indicates that it is taken up for revision. or of the latest amendments Monthly Additions'. Users of Indian Standards that they are in possession and `Standards: edition by referring to the latest issue of `BIS Catalogue' This Indian Standard has been developed Amendments Amend No. from Dot: No. ET 19 (5576). Issued Since Publication Text Affected Date of Issue BUREAU OF INDIAN STANDARDS Headquarters: Manak Bhavan, 9 Bahadur Shah Zafar Marg, New Delhi 110002 Telephones: 23230131,23233375,2323 9402 website: Regional Central Offices: : Manak Bhavan, 9 Bahadur Shah Zafar Marg NEW DELHI 110002 : 1/14 `C. I.T. Scheme Vll M, V.I.P. Road, Kankurgachi KOLKATA 700054 : SCO 335-336, Sector 34-A, CHANDIGARH 160022 www. bis.org. in Telephones 23237617 { 23233841 f"2337 8499,2337 `8561 123378626,23379120 2603843 { 2609285 22541216,22541442 { 22542519,22542315 28329295,28327858 { 28327891,28327892 COIMBATORE. FARIDABAD. Eastern Northern Southern : C.I.T. Campus, IV Cross Road, CHENNAI 600113 Western : Manakalaya, E9 MlDC, Marol, Andheri (East) MUMBAI 400093 AHMEDABAD. GHAZIABAD. NALAGARH. BANGALORE. BHOPAL. BHUBANESHWAR. Branches: GUWAHATI, HYDERABAD. JAIPUR. KANPUR. LUCKNOW. NAGPUR. PATNA. P!JNE. RAJKOT. TH}RUVANANTHAPURAM. VISAKHAPATNAM. Printed at Simco Printing Press, Delhi